State governments will still decide whether they want help from the military to handle terrorist incidents and police will remain the first responders under flagged changes, Prime Minister Malcolm Turnbull has said.

Announcing planned changes to the law at Holsworthy Barracks in Sydney on Monday morning, Mr Turnbull said the current process for calling in the military to help police during a terrorist attack was "very cumbersome" and needed to be streamlined.

Flanked by the Chief of the Defence Force Mark Binksin and standing in front of an inflatable boat with six heavily armed and masked special forces soldiers, Mr Turnbull said that currently states needed to "demonstrate that they have exhausted their ability to defend themselves".

"What we want to be able to do - and this is consistent with the constitution - is be in a position where a state government … can come to the conclusion that there is a special … niche assistance … required [then] it can be readily called upon and deployed."

The announcement to change the federal Defence Act – for which Labor has already offered bipartisan support – follows a lengthy review of the so-called "call-out" powers for when the Australian Defence Force can be used domestically in terrorist emergencies.

The changes will also boost training by army special forces of state police tactical units and embed military liaison officers who can advise police. Mr Turnbull said the changes would also improve the pre-positioning of the military for terrorist emergencies.

But the main change will remove from the Defence Act a clause that says the military can only be deployed if the state "is not, or is unlikely to be, able to protect itself against the domestic violence".

Constitutionally, states are responsible crime prevention. Under the Defence Act, they have to apply for help before the military can normally be deployed within Australia.

The ADF can however be deployed without a state government's request if the "Commonwealth interests" are threatened. These are not defined but have in the past been generally interpreted to include federal buildings and operations, from Parliament in Canberra to the operations of post offices or during federal elections.

The ADF has special forces "tactical assault groups" based in Sydney and Perth.

Holsworthy Barracks, where Mr Turnbull made the announcement, is home to the 2nd Commando Regiment who play a key role in counter-terrorism.

Labor Defence spokesman Richard Marles indicated broad support saying that while the opposition would study the detail of the legislative change, "I would expect we will fully support those measures".

Asked whether the government had used the ADF as props at the announcement given the striking imagery of the commandos, Mr Marles said he had not seen the images of the press conference but added that "there is a fine line between acknowledging and indeed celebrating the incredible work that our defence force personnel do on the one hand and politicising them on the other".

"The Australian people can well see a prop when it's presented. They can sniff it from a mile away and they will judge people accordingly," he said.